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AK+Kernel+LibELF: Remove the need for IteratorDecision::Continue

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By constraining two implementations, the compiler will select the best
fitting one. All this will require is duplicating the implementation and
simplifying for the `void` case.

This constraining also informs both the caller and compiler by passing
the callback parameter types as part of the constraint
(e.g.: `IterationFunction<int>`).

Some `for_each` functions in LibELF only take functions which return
`void`. This is a minimal correctness check, as it removes one way for a
function to incompletely do something.

There seems to be a possible idiom where inside a lambda, a `return;` is
the same as `continue;` in a for-loop.
This commit is contained in:
Nicholas Baron 2021-05-16 02:36:52 -07:00 • committed by GitHub
parent bbaa463032
commit aa4d41fe2c
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GPG key ID: 4AEE18F83AFDEB23
25 changed files with 311 additions and 127 deletions
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62
Userland/Libraries/LibELF/DynamicObject.h
View file

@ -8,6 +8,7 @@
#pragma once
#include <AK/Assertions.h>
#include <AK/Concepts.h>
#include <AK/RefCounted.h>
#include <AK/String.h>
#include <Kernel/VirtualAddress.h>
@ -125,8 +126,11 @@ public:
unsigned relocation_count() const { return entry_count(); }
Relocation relocation(unsigned index) const;
Relocation relocation_at_offset(unsigned offset) const;
template<typename F>
template<IteratorFunction<DynamicObject::Relocation&> F>
void for_each_relocation(F) const;
template<VoidFunction<DynamicObject::Relocation&> F>
void for_each_relocation(F func) const;
};
class Relocation {
@ -251,16 +255,18 @@ public:
ElfW(Half) program_header_count() const;
const ElfW(Phdr) * program_headers() const;
template<typename F>
template<VoidFunction<StringView> F>
void for_each_needed_library(F) const;
template<typename F>
template<VoidFunction<InitializationFunction&> F>
void for_each_initialization_array_function(F f) const;
template<typename F>
template<IteratorFunction<DynamicEntry&> F>
void for_each_dynamic_entry(F) const;
template<VoidFunction<DynamicEntry&> F>
void for_each_dynamic_entry(F func) const;
template<typename F>
template<VoidFunction<Symbol&> F>
void for_each_symbol(F) const;
struct SymbolLookupResult {
@ -341,7 +347,7 @@ private:
// End Section information from DT_* entries
};
template<typename F>
template<IteratorFunction<DynamicObject::Relocation&> F>
inline void DynamicObject::RelocationSection::for_each_relocation(F func) const
{
for (unsigned i = 0; i < relocation_count(); ++i) {
@ -353,16 +359,24 @@ inline void DynamicObject::RelocationSection::for_each_relocation(F func) const
}
}
template<typename F>
template<VoidFunction<DynamicObject::Relocation&> F>
inline void DynamicObject::RelocationSection::for_each_relocation(F func) const
{
for_each_relocation([&](auto& reloc) {
func(reloc);
return IterationDecision::Continue;
});
}
template<VoidFunction<DynamicObject::Symbol&> F>
inline void DynamicObject::for_each_symbol(F func) const
{
for (unsigned i = 0; i < symbol_count(); ++i) {
if (func(symbol(i)) == IterationDecision::Break)
break;
func(symbol(i));
}
}
template<typename F>
template<IteratorFunction<DynamicObject::DynamicEntry&> F>
inline void DynamicObject::for_each_dynamic_entry(F func) const
{
auto* dyns = reinterpret_cast<const ElfW(Dyn)*>(m_dynamic_address.as_ptr());
@ -374,21 +388,29 @@ inline void DynamicObject::for_each_dynamic_entry(F func) const
break;
}
}
template<typename F>
inline void DynamicObject::for_each_needed_library(F func) const
template<VoidFunction<DynamicObject::DynamicEntry&> F>
inline void DynamicObject::for_each_dynamic_entry(F func) const
{
for_each_dynamic_entry([func, this](auto entry) {
if (entry.tag() != DT_NEEDED)
return IterationDecision::Continue;
ElfW(Word) offset = entry.val();
StringView name { (const char*)(m_base_address.offset(m_string_table_offset).offset(offset)).as_ptr() };
if (func(StringView(name)) == IterationDecision::Break)
return IterationDecision::Break;
for_each_dynamic_entry([&](auto& dyn) {
func(dyn);
return IterationDecision::Continue;
});
}
template<typename F>
template<VoidFunction<StringView> F>
inline void DynamicObject::for_each_needed_library(F func) const
{
for_each_dynamic_entry([func, this](auto entry) {
if (entry.tag() != DT_NEEDED)
return;
ElfW(Word) offset = entry.val();
StringView name { (const char*)(m_base_address.offset(m_string_table_offset).offset(offset)).as_ptr() };
func(name);
});
}
template<VoidFunction<DynamicObject::InitializationFunction&> F>
void DynamicObject::for_each_initialization_array_function(F f) const
{
if (!has_init_array_section())